Lamp circuit



F. FUREDY LAMP CIRCUIT septgzs, i943.

Filed Dec. 16, 1940 l JAAAAAAI Patented Sept'. 28, 1943 LAMP CIRCUIT l Frank Furedy, Kraft, Inc., nois Chicago, Ill., assigner to Sun- Chicago, Ill., a corporation of Illi- Application December 16, 1940, Serial No. 370,271 8 Claims. (Cl. 176-124) This invention relates to a circuit for energizing a gaseous discharge lamp, particularly an ultra-violet or like therapeutic lamp.

It is an object of this invention to provide an electronic tube oscillator circuit of greater simplicity and compactness and less expensive from the manufacturing point of view so that the parts of such an oscillator circuit may be included in a restricted area and hence used to energize the gaseous discharge tube of an ultra-violet oor or table lamp.v

It is a further object of the invention to provide a one tube high frequency oscillating circuit capable of energization from the ordinary house circuit or circuit of similar voltage without use of a power transformer and which shall be capable of supplying a relatively large amount of power to energize an electrodeless gaseous discharge tube such, for example, as a fluorescent lamp or ultra-violet ray lamp for therapeutic treatments or other analogous use,

A further object of the invention is to provide a circuit employing only a single electronic tube for energizing the gaseous discharge tube from either an alternating current or a direct current source of standard house lighting voltage.

Applicants invention contemplates the pro vision of a high frequency power supply circuit capable of supplying power up to approximately eighty watts and which at the same time is of such simplicity in its number of parts that it may be mounted within an area of small volume, as, for example, within a hemispherical bowl or lamp base of a diameter of the order of ve inches.

Other and further objects and advantages of the invention will be apparent from the following description when taken in connection with the accompanying drawing, wherein the single figure is a schematic drawing of a circuit embodying the invention.

As shown inthe drawing, the lamp 2 which may be a quartz ultra-violet ray lamp or a uorescent lamp, comprises an electrodeless gaseous discharge tube exhausted to a high vacuum,

filled with mercury vapor, argon, neon, helium and krypton or other suitable rare gases and with a globule 4 of mercury, after which the lamp is sealed off.' High frequency voltage for the excitation of the lamp is supplied thereto by external clips, terminals or electrodes 6 which I mount the lamp in the reector as described 'in my copending application, Serial No. 347,257, led July 24, 1940.

A voltage is supplied to the terminals 6 through 55 the long leads 8 and H) which, in the lamp shown in said copending application, are of the order of thirty inches in length and are connected at their outer ends to plug terminals I2 fitting into the socket terminals I4 in the output of the high frequency generating or oscillating circuit I6. The circuit I6 comprises a thermionic vacuum tube I8. The tube I8 comprises a pair of cathodes 20 and 22, a pair of plates or anodes 24 and 26, a control grid 28, a screen grid 30, and a pair of series connected heater filaments 32 and 34. The series connected heater laments 32 and 34 are connected across the house circuit supply lines lL--I and L-2 or across other supply lines of similar voltage. The plate 24 is connected to the supply line L-I bythe wire 36. The cathode 20 is connected by the wire 38 to the screen grid 3U. The cathode 22 is connected by the wire 40 to the supply line L-2. coupled to the cathode 22 through a grid resistor 42 which is connected to the control grid by a wire 44 and to the supply line L-2. The control grid is also coupled to the end 58 of an air core induction coil or inductance 52 by the wire 44 and a wire 54 in which is interposed a condenser 56.

The plate or anode 26 is connected by a wire 58 to an intermediate tap 00` of the coil 52. 'Ihe screen grid 3|! is connected by the wires 62 and 64 to an intermediate tap 66 ofthe coil 52 andto the condenser 48.

The end 68 of the air core induction coil or inductance 52 is connected to the end 50 of the farads l 4. The induction coil 52 is of a number 23 cotton and enamel magnet wire of 72 turns wound on a inch tube, and the tap 66 is located at three turns from the end 50 and the tap 60 located at three turns from tap 66.

In operation, when the timing rswitch 16, of conventional construction and inthe line L-I is closed, current passes directly through the series 'I'he control grid 28 is 'taps 60 and 66 and causes 2 .t connected filaments 32 and 34 of the tube I8. When the line L-l is positive, current passes through the wire 36,.through the plate 24, the cathode 20, wire 38 and wires 62 and 64 to charge one plate of the condenser 48 which has its other side connected to the line L-2. In parallel to the condenser 48 current also passes from the wire 38 through the wire 62, tap 66, three turns of the coil 52, tap 60, wire 58, plate 26, the cathode 22 and the wire 40 to the supply line L-2.

As the charge is built up on the condenser 55 and then leaks away, a high frequency current is produced in the induction coil 52 at a frequency in the order of 550 kilocycles, suicient to excite the lamp 2 to luminescence, but the rays within the lamp do not extend completely from end to end of the tube and a slight flickering is observed. The portion of the induction coil 52 between the tap 60 and the end B8 when connected as shown reenforces the current from the portion of the coil between the end 50 and the the rays to extend completely from end to end of the lamp tube 2 and with a steady glow. l

The circuit shown in the drawing operates either on alternating current or direct current. In the case of direct current the circuit must be connected to the supply lines so that the cathode 22 is connected to the negative supply line and the plate 24 to the positive supply line.

The tube 2 may also be energized by placing it in the magnetic eld proximate to or within the coil 52.

It is obvious that various changes may be made in the specific embodiments of the invention set forth for purposes of illustration without departing [rom the spirit of the invention. Accordingly the invention is not to be limited to the speciiic embodiments shown and described but only as indicated in the following claims.

The invention is hereby claimed as follows:

1. A high frequency oscillating circuit for energizing a gaseous discharge tube comprising an electronic tube having plate, cathode and grid electrodes, a source of Voltage, an induction coil, aportion of said coil and said plate and cathode electrodes being connected in series across said source, a condenser connected in shunt with said coil portion and said plate and cathode electrodes, an impedance connected between said grid and cathode electrodes and a circuit shunting said impedance, said circuit including a condenser in series with another portion of said induction coil.

2. A high frequency oscillating circuit for energizing a gaseous discharge tube comprising an electronic tube havingy plate, cathode and grid electrodes, a source of voltage, an induction coil having a portion between spaced taps connected to one of said plate and cathode electrodes and one side of said source, the other of said plate and cathode electrodes being connected to the other side of said source, another portion of said induction coil being connected to said rst portion and to one of said grid and cathode electrodes, and an output circuit from said coil to said gaseous discharge tube and in whichsaid gaseous discharge tube is connected in series with both of said portions of the induction coil.

3. A high frequency oscillating circuit for energizing a gaseous discharge tube comprising an electronic tube having plate, cathode and grid electrodes, a source of voltage, an induction coil, a portion of said coil and said plate and cathode electrodes being connected in series across said source, another portion of said induction coil being connected across said grid and cathode electrodes, and an output circuit from said coil to said gaseous discharge tube and in which said gaseous discharge tube is connected in series with both of said portions of the induction coil, said induction coil having a third portion directly connected in shunt to said first and second portions in the output circuit to said gaseous discharge tube.

4. A circuit for energizing a gaseous discharge lamp from a standard alternating or direct current low voltage source,` comprising an electronic tube having rectifying electrodes and having plate, cathode and grid electrodes; an induction coil, a portion of said coil, said rectifying electrodes and said plate and cathode electrodes being connected in series across said source; and said induction coil having a portion connected to the first portion of said coil and to one of said grid and cathode electrodes.

5. A circuit for energizing a gaseous discharge lamp from a standard alternating or direct cur rent low voltage source, comprising an electronic tube means having rectifying electrodes and additional plate, cathode and grid electrodes; an induction coil, a portion of sa-id coil, said reetifying electrodes, and said plate and cathode electrodes being connected in series across said source, a power condenser in shunt to the series circuit of the first portion of said coil and said plate and cathode electrodes, a connection from said coil to said grid, and a resistor connected between said grid and cathode electrodes.

6. A circuit for energizing a gaseous discharge lamp from a standard alternating or direct current low voltage source, comprising an electronic tube having rectifying electrodes and additional plate, cathode, screen grid, and control grid electrodes; an induction coil; one of said rectifying electrodes being connected to one side of said source, and the other of said rectifying electrodes being connected to one of said screen grid and plate electrodes; said coil having spaced intermediate taps, one of which is directly connected to said other rectifying electrode, the other of said taps being connected to the other of said plate and screen grid electrodes; a grid condenser connected to one end of said coil and to said control grid; a resistor connected between' said grid and cathode electrodes; a connection from said cathode electrode to the other side of said source; a power condenser connected between said other side of said source and said other rectifying electrode; and a direct conductive connection between the opposite ends of said coil.

7. A circuit forenergizing a gaseous discharge lamp fromv a standard alternating or direct current low voltage source, comprising an electronic tube having rectifying electrodes and additional plate, cathode, screen grid, and control grid electrodes; an induction coil; one of said rectifying electrodes being connected to one side of said source, and the other of said rectifying electrodes being connected to one of said screen grid and plate electrodes; said coil having spaced intermediate taps, one of which is directly connected to said other rectifying electrode, the other of said taps being connected tothe other of said plate and screen grid electrodes; a grid condenser connected to one end of said coil and to said control grid; a resistor connected between said grid and cathode electrodes; a connection from said cath- 0de electrode to the other side of said source; a power condenser connected between said other side of said source and said other rectifying elecinduction coil, a circuit including in series a portion of said coil and said plate and cathode elec- 10 trodes,4 a. condenser connected in shunt to that portion of the circuit that includes the coil portion in series with the plate and cathode elec- Y trodes, and a second circuit in conductive shunt to said portion of said coil and including in series another portion of said coil, and a leak impedance, said leak impedance being directly connected at its opposite ends to said grid and cathode electrodes.

FRANK FUREDY. 

